Floor finishing machine



p 1, 1964 G. w. WILKINSON 3,146,559

FLOOR FINISHING MACHINE Filed Feb. 4, 1963 3 Sheets-Sheet l mix \- ORNEY 5 w ATT Sep 1964 G. w. WILKINSON FLOOR FINISHING MACHINE 3 Sheets-Sheet 2 Filed Feb. 4, 1963 INVENTOR GEa/PGE W. Mun/v30 Sept. 1, 1964 G. w. WILKINSON 3,146,559

FLQOR FINISHING MACHINE Filed Feb. 4, 1963 3 Sheets-Sheet 3 INVENTOR Gap/P 5 14 Mz/(m so/v ATTORNE Y United States Patent 3,146,559 FLGUR FfillSHlNG MAQIHHJE George W. Wilkinson, Mine Road, RD. 2, Somerviile, NJ. Fitted Feb. 4, H63, Ser. No. 256,630 9 Ciairns. (Cl. 51-177) This invention relates in general to floor grinding machines and in particular to improvements in machines used to grind terrazzo floors. The invention relates specifically to a novel combination of elements which cooperate to produce a grinding machine capable of surfacing -a greatly increased amount of floor area per unit of time at the least possible cost.

Terrazzo floors are fabricated by using small chips of marble as .the principal aggregate in cement. It is customary after the cement has set to grind off the surface roughness of the floor with a floor surfacing machine to expose and polish the marble aggregate chips and give such fioors their characteristic appearance. While such floors have a fairly high cost per unit area in comparison to alternate flooring materials, such additional cost has generally been found to be justified in the construction of commercial buildings because of their low subsequent upkeep expense, easy maintenance and good wearing ability.

Because a large proportion of the cost of a terrazzo floor is associated with the labor involved in the finishing operation, and the fact that labor costs generally have risen substantially in the cement finishing industry in comparison to the labor cost in the other floor finishing techniques, the price spread therebetween has widened in recent years. Also affecting the competitiveness of terrazzo floors with other floor materials are the recent technological advances made in, for instance, vinyl plastic floor tiles which have many competitive aspects in their favor "one of which includes a lower initial cost. The lower cost of vinyl, and its wide range of available colors has led to its use in commercial buildings hithertofore employing terrazzo.

Accordingly, it is the principal object of this invention to significantly lower the labor cost per unit area of terrazzo floor so that this type flooring remains competitive with alternate types of floor coverings.

This principal object of the applicants invention is accomplished by applicants novel arrangement of a simple high speed surface grinding machine capable of production rates considerably in excess of any present day machine constructed for similar purposes. Applicants novel arrangement includes the use of a multiplicity of diamond abrasive cutting heads secured, as by Welding, in an annular ring to the lower surface of a rotatable plate. Each plate is directly connected through a flexible coupling to a hollow output shaft of its respective drive motor. In applicants novel arrangement the diamond grinding heads are mounted in adjacent pairs and connected for opposite, torque balancing rotations. The drive shaft of each of the motors is tubular to allow passage therethrough of a water supply conduit which discharges water through an aperture in the flexible coupling and through a corresponding aperture in the grinding head to supply water centrally to the diamond abrasive wheel. Applicants invention includes the specific arrangement of the diamond abrasive seg ments on the grinding head in a novel manner so that the cent-rally discharged cutting lubricant is not only maintained under the grinding head by a centripetal pumping action thereof, but the peripheral water lying on the floor being finished is picked up and impelled inwardly thereby toward the center of rotation of the head.

The invention as embodied includes four individual drive motors arranged in rectangular relation, adjacent motors being adapted to rotate in opposite torque balancing rotation. In applicants preferred embodiment 5 hp., 1750 rpm. motors are used. Coupled directly thereto via flexible couplings are the grinding discs mounting the spaced diamond abrasive portions. Cutting lubricant, such as water, is fed under pressure downwardly through each of the drive motor tubular armature shafts, through an aligned central aperture in the flexible coupling, through the center of the lower surface of the grinding head. The selection of diamond abrasive means, which may be, and preferably are rotated at a high rpm. in comparison to typical prior art grinding machines, permits the elimination of the hither-tofore common reduction gear drive employed therein. Prior art machines employing carborundum grinding heads operate most efiiciently at a low rpm. and invariably incorporate complex reduction gearing so that adequate torque could be applied thereto from a small high speed motor.

The present invention eliminates the costly gear drive arrangement of typical prior art machines by providing a diamond surfaced cutter capable of optimum performance at standard motor speed of 1750 to produce a floor finishing machine capable of area production rates 50% greater than typical prior art arrangements. Because of applicants increased surface finishing capability per machine, the cost of terrazzo floors has been maintained competitive with alternate surface finishes in spite of the labor wage spiral experience in this industry.

Accordingly, a principal object of the present invention is to produce a novel combination of elements which form a high speed grinding machine capable of grinding a greatly increased amount of floor space per unit of time.

A further object of the invention is to provide a gearless terrazzo floor finishing machine wherein the grinding heads operate at the same high speed as the driving motors.

Another object of the invention is to provide a high speed terrazzo floor finisher employing diamond abrasive grinding segments arranged in a spaced spiral relation to enhance cutting lubrication efiiciency.

Another object of the invention is to provide a terrazzo floor finisher wherein the grinding heads have negligible wear.

Another object of the invention is to provide a floor finisher employing four drive motors and individual grinding heads attached to the output shafts of each of said motors.

A further object of the invention is to provide a floor finisher which is extremely simple in design, employs a minimum number of parts, rugged in construction, trouble free in operation, low in maintenance and economical to manufacture.

These and other objects and advantages will become apparent and the invention will be fully understood from the following description and drawings in which:

FIG. 1 is a perspective view of the machine according to the invention;

FIG. 2 is a top plan view of the motor portion of the machine;

FIG. 3 is a bottom plan view showing the quadruple grinding heads of the invention;

FIG. 4 is a side elevational view of the machine with portions thereof in section;

FIG. 5 is an enlarged fragmentary sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is a fragmentary bottom view of the cutter head with portions broken away to show the universal coupling;

FIG. 7 is a fragmentary sectional view of the grinding head coupling arrangement taken along line 7-7 of FIGS. 5 and 6; and

FIG. 8 is a fragmentary cross-sectional view of the invention taken along line 8--8 of FIG. 3.

Referring to the drawing in particular, the floor grinding machine shown generally at 10 includes a horizontially extending frame plate 12 to which is welded a centrally located tubular support column 14 extending upwardly therefrom. The upper end of the support column 14 includes a threaded portion (FIG. 4) to wh1ch is secured a threaded cap 16. Extending through the center of the cap 16 and threaded thereto is a crank arm 18 whose lower end' contacts a cup-shaped member 20. Axially beneath the cup 20 is a coil support spring 22 whose lower end abuts the upper end of a main support post 24.

The support post 24 (see FIGS. 4 and 8) extends downwardly through the column 14 to connect at its lower end with a U-shaped channel cross member 26. The cross member 26 includes a pair of downwardly depending ear portions 27 which provide support means for opposite ends of a pivot bolt assembly 28. The bolt 28 passes through a transverse axle 30 which mounts wheels 32 at opposite ends thereof. A pair of guide rods 34 are secured at their lower ends to the upper surface of the cross member 26 and extends upwardly through clearance apertures 38 in the frame plate 12 to prevent relative rotation between the frame and the axle member. The upper ends of each of the guide rods 34 includes a transverse pin 36 to prevent the dropout of the wheel assembly upon elevation of the machine.

Bolted, or secured by other means, to the upper surface of the frame 12 are four vertically disposed drive or grinding motors 40. The motors are preferably arranged as indicated in a contra-rotating first pair forward of the wheels 32 and a contra-rotating second pair aft thereof. The upper end of each of the motor 40 casings is secured to a rectangular plate 42 which acts to provide a mounting surface for purposes described herebelow, and at the same' time to rigidify the uppermost ends of the motor housings. Extending obliquely upward from a central portion of the plate 42 are a pair of parallel tubular members 46" which connect with a transverse operators handle 44 at their uppermost ends. Secured to the members 46' is a motor control box 48 which contains the conventional necessary starting controls for the individual motors 40. An electrical feed cable (not shown) supplies the necessary energy to the control box 48 which is channeled via connecting cables 50 to the individual drive motors 40.

Each of the motors 40 includes a tubular armature output shaft 52 which extends downwardly through a clearance aperture in the plate 12.

An annular collar or bushing 54 is secured, as by threads, to the lower end of the output shaft 52 to act as a bearing for the support of the lower end of a water supply conduit 58 extending downwardly throughout the length of the tubular shaft 52. While not specifically'shown, it should be understood that each of the motor output shafts includes a similar conduit 58 and that each are connected in common by a pipe manifolding arrangement 60. The cross'member 61 of the pipe 60 joins with a flexible hose member 62 which includes a flow control adjustment valve 64 therein. The valve 64 is disposed adjacent the operators handle 44 to facilitate easy adjustment of the water flow during operation of the machine. The output torque of each motor shaft 52 is transmitted downwardly to their respective grinding head 66 via an intermediate flexible coupling shown generally as 68. Each coupling 68 includes an upper cross arm 70 keyed to the lower end of the output shaft 52. A central spider member 72 includes a pair of complementary upper and lower steel shells 76 which are secured together to encase opposite pairs of resilient bushings 74 therebetween. (Refer to FIGS. 5, 6' and 7.) One pair of the bushings 74 is secured by a pair of bolt members 78 and stepped spacers 80 to cross member 70. The other pair of resilient bushings 74 is similarly attached by bolts 82- and spacers 84 to the circular 4 support plate 88 of the grinding head 66. The shells 76 and the circular plate 33 include central apertures 86 and 92, respectively, which allow passage of the water discharged from the lower end of the conduit 58 vertically downward to the center of rotation of the grinding head 66.

Each head 66 includes a plurality of elongated rectangularly-shaped diamond abrasive blocks fit) secured, as by brazing, in spiral or oblique relation to the outer periphery thereof. The longitudinal axis of each abrasive block 9% is inclined at an acute angle of approximately 25 relative to a radial line extending from the center of the plate 88 through the outermost tip of the block 90. The orientation of the diamond abrasive blocks is effective to retard the outward flow of the cutting lubricant from under the head as well as to inwardly impel any liquid that the head tends to pick up at its periphery as it is moved by its operation about the terrazzo floor. The blocks 90 are inclined with their outermost ends pointing in the direction of rotation of the shaft of the drive motor. As is best shown in FIG. 3, it can readily be seen that the left-most pair of heads 66 have opposite directions of rotation as do the right hand most pair of heads 66. However, it should also be noted that the uppermost horizontal pair of heads also have contra-rotating directions as do the bottommost horizontal pair of heads. In this manner, counterbalancing cutting torques will always occur regardless of whether the majority of the weight is supported by the fore or aft pair of grinding heads or alternatively by the left or right pair of grinding heads. It should also be noted that the adjustment of the crank arm 18 is effective to raise or lower the entire motor and frame assembly upwardly from the wheels to thereby alter the cutting force on the grinding heads 66 and that the entire assembly is free to Wobble within confined limits in both a transverse and longitudinal axis about the pivot bolts 28 and wheels 32. The frame is also provided with an upstanding counterweight in the form of a lead filled pipe 28 which balances the weight of the control box 48.

Each of the pairs of grinding head means 66 is surrounded by an oval-shaped skirt member 94 which acts to prevent undue splashing of lubrication liquid from the periphery of the heads. Because applicants diamond abrasive cutting heads have little and almost insignificant wear or change in dimension throughout their life, the splash skirt 94 may be directly secured to the edge of the plate 12 without provision of height adjustment thereof, as is necessary for an effective splash plate about a carborundum wheel which will wear with usage.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What I claim is:

l. A surface grinding machine comprising a frame, a first pair of drive motors mounted on said frame each having a tubular output shaft disposed in a substantially vertical relation, said motors connected to have their respective shafts rotate in opposite directions, a second pair of drive motors mounted on said frame each having a substantially vertical tubular output shaft parallel to the output shafts of said first pair of motors, said second pair of drive motors being connected to have their respective shafts rotate in opposite directions to each other and in opposite directions to the direction of rotation of the adjacent drive motors of the first pair, a plurality of circular grinding means, means for flexibly coupling each of said grinding means directly to the lower end of each output shaft, and means for supplying a cutting lubricant downwardly, under pressure, through each motor output shaft to the center of its respective grinding means, said grinding means including a plurality of spaced elongated diamond abrasive means, said abrasive means being ar- 3 ranged about the periphery of said grinding means with the longitudinal axis thereof angularly acute to the radius of said circular grinding means and having their outermost ends pointed in the direction of rotation of its respective grinding means whereby the outward flow of cutting lubricant is retarded by the centripetal pumping effect of said abrasive means.

2. A surface grinding machine according to claim 1 including wheel means for movably supporting said frame above the surface to be ground, and means securing said wheel means to said frame between said first and second pair of drive motors, said securing means including means for allowing a limited longitudinal and transverse rocking of the frame relative to the surface to be ground.

3. A surface grinding machine according to claim 2 including means for adjusting the height of said frame above the level of said wheel means.

4. A surface grinding machine according to claim 2 including plate means affixed to the upper ends of each of said drive motors, and control means secured to said plate means, said control means including means for starting said drive motors and means for regulating the flow of cutting lubricant through the motor output shafts.

5. A surface grinding machine according to claim 3 including in addition a pair of oval skirt means rigidly secured to said frame, said skirt means respectively peripherally enclosing the grinding means of said first and second pair of drive motors.

6. A surface grinding machine according to claim 5 including counterweight means affixed to said frame for offsetting the weight of said control means thereby balancing said machine symmetrically about said wheel means.

7. A surface grinding machine comprising a pair of drive motors each having a tubular output shaft and connected to have their respective shafts rotate in opposite directions, a pair of circular grinding means, means for flexibly coupling each of said grinding means directly to the lower end of each motor output shaft, and means for supplying a cutting lubricant downwardly under pressure through each output shaft to the center of its respective grinding means, each grinding means including a plurality of spaced elongated diamond abrasive means, said abrasive means being arranged about the periphery of said grinding means with the longitudinal axis thereof angularly acute to the radius of said circular grinding means and having their outermost ends pointed in the direction of rotation of its respective grinding means whereby the outward fiow of cutting lubricant is retained by the centripetal pumping effect of said abrasive means.

8. A surface grinding machine comprising a pair of drive motors each having a tubular output shaft and connected to have their respective shafts rotate in opposite directions, a pair of circular grinding means, means for flexibly coupling each of said grinding means to the lower end of each motor output shaft coaxially therewith, and means for supplying a cutting lubricant downwardly under pressure through each output shaft to the center of its respective grinding means, each grinding means including a circular plate, a plurality of spaced elongated abrasive means, said abrasive means being fixedly attached to said plate and oriented thereon in such a manner with regard to the direction of rotation of its associated output shaft that the outward flow of the centrally fed cutting lubricant is retarded by the centripetal pumping effect of said abrasive means.

9. A surface grinding machine comprising a frame, a first pair of drive motors mounted on said frame each having a tubular output shaft disposed in a substantially vertical relation, said motors connected to have their respective shafts rotate in opposite directions, a second pair of drive motors mounted on said frame each having a substantially vertical tubular output shaft parallel to the output shafts of said first pair of motors, said second pair of drive motors being connected to have their respective shafts rotate in opposite directions to each other and in opposite directions to the direction of rotation of the adjacent drive motors of the first pair, a plurality of circular grinding means, means for flexibly coupling each of said grinding means to the lower end of each output shaft coaxially therewith, and means for supplying a cutting lubricant downwardly, under pressure, through each motor output shaft to the center of its respective grinding means, each grinding means including a circular plate, a plurality of spaced elongated abrasive means, said abrasive means being fixedly attached to said plate and oriented thereon in such a manner with respect to the direction of rotation of its associated output shaft that the outward flow of the centrally fed cutting lubricant is retarded by the centripetal pumping effect of said abrasive means.

References Cited in the file of this patent UNITED STATES PATENTS 1,032,023 Prugh July 9, 1912 1,069,803 Nelson et al Aug. 12, 1913 1,116,145 Smith Nov. 3, 1914 1,302,404 Mills Apr. 29, 1919 1,452,926 Orlando Apr. 24, 1923 2,106,035 Mall Jan. 18, 1938 2,171,060 DeSpirt Aug. 29, 1939 2,793,476 Lombardo May 28, 1957 2,883,807 Titcomb Apr. 28, 1959 2,913,855 Vinella Nov. 24, 1959 FOREIGN PATENTS 156,388 Switzerland Oct. 17, 1932 530,723 Great Britain Dec. 18, 1940 

8. A SURFACE GRINDING MACHINE COMPRISING A PAIR OF DRIVE MOTORS EACH HAVING A TUBULAR OUTPUT SHAFT AND CONNECTED TO HAVE THEIR RESPECTIVE SHAFTS ROTATE IN OPPOSITE DIRECTIONS, A PAIR OF CIRCULAR GRINDING MEANS, MEANS FOR FLEXIBLY COUPLING EACH OF SAID GRINDING MEANS TO THE LOWER END OF EACH MOTOR OUTPUT SHAFT COAXIALLY THEREWITH, AND MEANS FOR SUPPLYING A CUTTING LUBRICANT DOWNWARDLY UNDER PRESSURE THROUGH EACH OUTPUT SHAFT TO THE CENTER OF ITS RESPECTIVE GRINDING MEANS, EACH GRINDING MEANS INCLUDING A CIRCULAR PLATE, A PLURALITY OF SPACED ELONGATED ABRASIVE MEANS, SAID ABRASIVE MEANS BEING FIXEDLY ATTACHED TO SAID PLATE AND ORIENTED THEREON IN SUCH A MANNER WITH REGARD TO THE DIRECTION OF ROTATION OF ITS ASSOCIATED OUTPUT SHAFT THAT THE OUTWARD FLOW OF THE CENTRALLY FED CUTTING LUBRICANT IS RETARDED BY THE CENTRIPETAL PUMPING EFFECT OF SAID ABRASIVE MEANS. 